1. Field of the Invention
This invention relates to color photography and, more particularly, it relates to a light-sensitive color photographic material wherein color fog and stains are effectively prevented and color images of good color separation are obtainable.
2. Description of the Prior Art
For the formation of color photographic images based on a subtractive color process, the steps of forming cyan, magenta, and yellow dye images by the coupling of dye-forming couplers with the oxidation product of generally an aromatic primary amine compound, and in particular a N,N-di-substituted p-phenylenediamine compound, developing agent formed by reducing the exposed silver halide grains in photographic emulsion layers are utilized.
The couplers used for the color development are compounds which have a phenolic hydroxyl group, an anilinic amino group, or an active methylene group and form dyes capable of absorbing light in a visible wave-length region by the oxidative coupling with the aromatic primary amine developing agent.
As the magneta-forming couplers, pyrazolones are generally known. Of the pyrazolone couplers, the 3-anilino-5-pyrazolone compounds have long been known as good magenta-forming couplers in the field of color photography as described in, for instance, the specification of U.S. Pat. No. 2,311,081 (Reissue 22,329) and also, in British Pat. No. 956,261, an azomethine dye obtained from a 3-anilino-5-pyrazolone derivative substituted with an alkoxyl group or a halogen atom in the ortho-position of the anilino group is described as having a useful spectral absorption for color photography and also the description is that the unnecessary absorption in the red light region is particularly less. Non-diffusible couplers which belong to this type of coupler and can be incorporated in photographic emulsions are described in the specifications of U.S. Pat. Nos. 3,127,269, 3,658,544, 2,684,516, 3,419,391 and 3,519,429, and Japanese patent application Nos. 114,446/1972, 114,445/1972, and 21454/1973 and German OLS 2,133,655. Of these 3-anilino-5pyrazolone couplers, the couplers in which the ortho-position of the anilino group at the 3-position has been substituted with a halogen atom, an alkyl group, an alkoxyl group, a nitro group, a cyano group, a hydroxyl group, or an amide group and which has at least one hydrophobic residue having 8 to 32 carbon atoms are most excellent at present in that the couplers provide color images having sharp spectral absorption curve and less unnecessary absorption in the red region and the blue region and that the couplers show excellent coupling or coloring at color development. However, in spite these excellent advantages as shown above, magenta dye-forming couplers of this type do not provide satisfactory color photographic materials using conventional techniques for the following reasons. That is to say, the couplers suffer from severe magenta fogging at color development of the color photographic materials containing the magenta dye-forming couplers, yellow stains are readily formed in the color photographic materials containing the magenta dye-forming couplers with the passage of time after processing due to the action of the formaldehyde used in the hardening or the dye image stabilization during color processing, color mixing occurs greatly between the photosensitive emulsion layer containing the magenta dye-forming coupler and other photosensitive emulsion layers, and further the magenta dye-forming couplers tend to be oxidized during the addition of the couplers to photographic emulsions in the production of color photographic materials.
The development of a technique for using these substituted 3-anilino-5-pyrazolone couplers as described above in color photographic materials unaccompanied by the above-described disadvantages has, thus, been desired.